For many years, fiberboards have been manufactured from wood or agricultural substrates using thermosetting binders. Formaldehyde-based binders, such as urea formaldehyde and melamine formaldehyde have traditionally dominated the fiberboard industry during that time. Wood composites made with an adhesive binder containing a formaldehyde-based resin have generally been limited to applications where exterior durability is not required. Unfortunately, one of the drawbacks of using formaldehyde-based resins as a component of wood composite adhesive binders is that such resins may release a small amount of formaldehyde.
Isocynate-based binders, particularly diphenylmethane diisocyanate (MDI) binders, however, offer some significant advantages over formaldehyde-based binders, including superior physical and moisture-resistance properties and the elimination of formaldehyde emission hazards. Although isocyanate binder technology for fiberboard manufacture has been available for many years, isocyanates have not gained widespread commercial acceptance, primarily because of cost. MDI-based isocyanates tend to be more expensive per pound than formaldehyde-based binders, but are used at a lower dose rate, partially offsetting the cost disadvantage.
As such, there is a continuing need for identifying new adhesive binder compositions suitable for making wood and other composites, which have an improved physical properties and are safe to use.